the iso approach to the development of ergonomics ...the group behind the software parts of iso 9241...

Jan Gulliksen, Susan Harker and John Steger.

CID, CENTRE FOR USER ORIENTED IT DESIGN

CID-121 ISSN 1403 -0721 Depa r tmen t o f Numer i ca l Ana l ys i s and Compu te r Sc ience KTH

The ISO Approach to the Development of ErgonomicsStandards for Accessibility

Författare: Jan Gulliksen, Susan Harker and John Steger

The ISO Approach to the Development of Ergonomics Standards for Accessibility.Report number: CID-121ISSN number: ISSN 1403-0721 (print) 1403-073X (Web/PDF)Publication date: 2001E-mail of author: [email protected] of author: http://cid.nada.kth.se

Reports can be ordered from:

CID, Centre for User Oriented IT DesignNADA, Deptartment of Numerical Analysis and Computer ScienceKTH (Royal Institute of Technology)SE-100 44 Stockhom, SwedenTelephone: + 46 (0) 8 790 91 00

Fax: + 46 (0) 8 790 90 99

E-mail: [email protected]: http://cid.nada.kth.se

CHAPTER NUMBER

ISO 16071 Ergonomics of human-system interaction – guidance on

software accessibility

Jan Gulliksen1,2 ([email protected]),Susan Harker3 ([email protected]),

John Steger4 ([email protected]),

1Department of HCI, Information Technology, Uppsala University, Uppsala,Sweden2Center for user-oriented IT-design (CID), Royal Institute of Technology,Stockholm, Sweden3Loughborough Institute of Technology, United Kingdom4IBM, United States of America

ABSTRACT

This chapter reports on the work currently performed by the InternationalOrganization for Standardization (ISO) on accessibility of human-computerinterfaces. ISO Technical Specification 16071 “Ergonomics of human-systeminteraction – guidance on software accessibility” will be published by the end of2000.

INTRODUCTION

With the increasing interest in designing usable systems and the increasing thelevel of accessibility for people with specific potential requirements, theInternational Organisation for Standardisation has been conducting work resultingin a ISO Technical Specification 16071 Ergonomics of human-system interaction –guidance on software accessibility.

Here I would like an introduction that stresses the importance of addressingthe growing population of users who need extra support to be able to handlecomputer support. How big are these groups? I know that we can find informationin the Nordic guidelines.

What are the incitements to support this type of work? E.g. referencing ADA(American Disabilities Act)

INTERNATIONAL ORGANISATION FOR STANDARDIZATION (ISO)

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The International Organization for Standardization (ISO) is a worldwide federationof national standards bodies from some 130 countries, one from each country. ISOis a non-governmental organisation established in 1947. The head office is inGeneva. The mission of ISO is to promote the development of standardisation andrelated activities in the world with a view to facilitating the international exchangeof goods and services, and to developing co-operation in the spheres ofintellectual, scientific, technological and economic activity. ISO's work results ininternational agreements, which are published as International Standards.

ISO standards are developed according to the following principles:• Consensus – The views of all interests are taken into account: manufacturers,

vendors and users, consumer groups, testing laboratories, governments,engineering professions and research organisations.

• Industry-wide – Global solutions to satisfy industries and customersworldwide.

• Voluntary – International standardisation is market-driven and therefore basedon voluntary involvement of all interests in the marketplace.

The international standard described in this document is provided by ISO TC159/SC 4/WG 5 “Software ergonomics and human computer dialogues”. WG 5 isthe group behind the software parts of ISO 9241 “Ergonomic requirements foroffice work with visual display terminals (VDTs)”, that is parts 10 through 17.WG 5 is also currently preparing ISO 14915 “Multimedia User Interfaces”.

Guidance on Accessibility of Human Computer Interfaces – ISO 16071 is notan international standard, but a Technical Specification (TS). A TS is a new formatfor ISO documents presented at first in 1998. It is a normative documentrepresenting the technical consensus within an ISO committee. The purpose is thata technical specification within a period of six years should be converted into aninternational standard or be withdrawn.

THE INTRODUCTION TO ISO TS 16071

The purpose of ISO Technical Specification 16071 is to provide guidance todevelopers on designing human-computer interfaces which can be used with ashigh level of accessibility as possible. Designing human computer interactions toincrease accessibility promotes increased effectiveness, efficiency, and satisfactionfor people who have a wide variety of capabilities and preferences. Accessibility istherefore strongly related to the concept of usability (ISO 9241 Part 11 – Guidanceon usability).

The most important methodological approaches to increase the accessibilityof a given human-computer interface are:• Task-oriented design of user interfaces.• Customisation• The use of human centred design principles (ISO 13407 - Human centred

design process for interactive systems).• Individualised user instruction and training.

The focus of ISO TS 16071 is development of human computer interactions to

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systems and products that are intended for use by the widest range of people withspecial needs. An important part of a human centred design process for accessiblesystems is to develop human-computer interfaces to meet accessibility goals thatcan be quantitatively evaluated for a specific user or user category in a specifiedcontext of use.

The ISO Technical Specification 16071 is based mainly on the prevalentknowledge of individuals with sensory and/or motor impairments in an officework context. However, accessibility is an attribute that affects a large variety ofcapabilities and preferences of human beings. These different capabilities may bethe result of age, disease, and/or disabilities. Therefore, accessibility addresses awidely defined group of users including:• people with physical, sensory and cognitive impairments by birth or acquired

during life• elderly people who can benefit from new IT products and services but

experience reduced physical, sensory and cognitive abilities• people with temporary disabilities such as a person with a broken arm or

someone who forgot her glasses• people who are experiencing difficulties in certain situations, such as a person

who works in a noisy environment or has both hands occupied by other work.

Having a disability should be regarded as a natural element of the life cycle. Everyone can expect, during some period of life, to be affected by circumstancesthat make the access to ad use of IT systems products and services difficult.

ISO TS 16071 recognises that some users will always need assistive devicesto use a system. Therefore, it includes the capability of a system to connect andinteract successfully with assistive technologies in the concept of accessibility. ISO TS 16071 provide guidance for system design, appearance andbehaviour. The guidance will allow software to be used by as broad an audience aspossible. In addition, guidance will be provided on designing software tointegrate as effectively as possible with common assistive technologies (e.g.,speech synthesisers, Braille input and output devices) when they are available.Incorporating accessibility features early in the design process is relativelyinexpensive compared to the cost of modifying products to become accessible.

ISO TS 16071 addresses the increasing need to consider the social andlegislative demands to ensure accessibility by removing barriers that prevent themfrom participating in life activities including the use of environment, services,products, and information. Designing software user interfaces for accessibilityincreases the number of people who can use computer systems by taking intoaccount the varying physical and sensory capabilities of user populations.Designing for accessibility benefits disabled users by making software easier forthem to use or making the difference in whether they are able to use the software atall.

Many accessibility features also benefit users who are not handicapped byenhancing usability and providing additional customisation possibilities. Theymay also help to overcome temporary deficits (e.g., a broken arm or hand). ISOTS 16071 benefits designers and suppliers by expanding the number of potentialusers (and thus sales for their product) and often by making the product compliantwith legal requirements for accessibility. It benefits companies buying software by


expanding the number of employees who may use the software.Accessibility may be provided by a combination of both hardware and

software. Assistive technologies typically provide specialised input and outputcapabilities not provided by the system. Software examples include on-screenkeyboards that replace physical keyboards, screen magnification software thatallows users to view their screen at various levels of magnification, and screenreading software that allows blind users to navigate through applications,determine the state of controls, and read text via text to speech conversion.Hardware examples include head-mounted pointers that replace mice and Brailleoutput devices that replace a video display. There are many other examples notlisted here. When users provide add-on assistive software and/or hardware,usability is enhanced to the extent that systems and applications integrate withthose technologies. For this reason, operating systems may have to provide“hooks” or other features to allow software to operate effectively with add-onassistive software and hardware as recommended in these guidelines. If systems donot provide support for assistive technologies, the probability increases that userswill encounter problems with compatibility, performance, and usability. At thesame time, if software applications do not use system provided mechanisms (suchas customisation for colour, font, and audio, or system routines for keyboardnavigation and text input), then users can find their access blocked.

SCOPE OF THE ISO 16071

ISO Technical Specification 16071 provides guidance on design of accessible(work, home, education) software. It covers issues associated with designingaccessible software for the widest range of visual, hearing, motor and cognitiveabilities, including people who are elderly and temporarily disabled. ThisTechnical Specification addresses software considerations for accessibility thatcomplements general usability design covered by ISO 9241 and ISO 13407.

The Technical Specification covers accessibility of computer operatingsystems and applications. While it does not address all accessibility issues ofplatforms and application domains such as web pages, multimedia, PersonalDigital Assistants (PDA), and kiosks, many of the recommendations are applicablein these areas. It does not apply to software used primarily for entertainmentpurposes (i.e., games). It does not provide recommendations for the design ofhardware.

The Technical Specification is aimed at reducing the need for add-on assistivehardware and software technologies while promoting increased usability of systemsin combination with assistive technologies, when they are required. It does notcover the behaviour or requirements for assistive technologies themselves(including assistive software).

DEFINING ACCESSIBILITY IN RELATION TO USABILITY

Our experience from the development and use of ISO 9241 part 11 is the benefitsof having a clear and succinct definition of the concept. ISO 9241:11 defines


usability as:

The extent to which a product can be used by specified users, to achieve specifiedgoals, with effectiveness, efficiency and satisfaction, in a specified context of use.

The advantage of such a definition is both that it defines usability to be aquantitatively measurable concept. It also emphasises the non-functional demandsof usability that is so important for the final interpretation of the concept.

On the other hand we would want to define accessibility in relation tousability as a measurable entity. Therefore ISO TS 16071 define accessibility as:

The usability of a product, service, environment or facility by people with thewidest range of capabilities.

This definition implicitly indicates that it is measurable through its relation tousability. However, it is extended to cover more than just products (as in thedefinition of usability), covering service, environment or facility. This definitioncan be compared to the less precise definition from HFES 200 Software UserInterfaces – Accessibility:

The set of properties that allows a product, service or facility to be used bypeople with a wide range of capabilities, either directly or in conjunction withassistive technologies. Although “accessibility” typically addresses users whohave a disability, the concept is not limited to disability issues.

This definition suggests accessibility as of a binary nature, i.e. either a product isaccessible or not. This does not correspond with essence of the specific guidelinesin the document, why we suggest sharpening the definition to be quantitativelymeasurable. As a comparison, the World Wide Web Consortium (W3C) defineaccessibility in the following way:

Content is accessible when it may be used by someone with a disability.

Measurable accessibility should be measured in terms of users, task, context andproducts. To be able to compare the accessibility one must only vary one of theseterms at a time, e.g.:

Accessibility1=f(user1, task1, context1, product1)Accessibility2=f(user1, task1, context1, product2)

RATIONALE AND BENEFITS OF ISO 16071

Accessibility is an important consideration in the design of products, systems,environments and facilities because if effects the usability of people with thewidest possible range of capabilities.

Accessibility can be improved by incorporating features and attributes knownto benefit the users with specific special requirements. In order to determine the


achieved level of accessibility, it is necessary to measure the performance andsatisfaction of users working with a product or interacting with an environment.Measurements of accessibility is particularly important in view of the complexityof the interactions with the user, the goals, the task characteristics and the otherelements of the context of use. A product, system, environment or facility canhave significantly different levels of accessibility when used in different contexts.

Planning for accessibility as an integral part of the design and developmentprocess involves the systematic identification of requirements for accessibilityincluding accessibility measurements and verification criteria within the context ofuse. These provide design targets that can be the basis for verification of theresulting design.

The approach adopted in ISO Technical Specification 16071 has benefits,which include:• The framework can be used to identify the aspects of accessibility and the

components of the context of use to be taken into account when specifying,designing or evaluating the accessibility of a product.

• The performance (effectiveness and efficiency) and satisfaction of the users canbe used to measure the extent to which a product, system, environment orfacility is accessible in a specific context.

• Measures of the performance and satisfaction of the users can provide a basisfor the comparison of the relative accessibility of products with differenttechnical characteristics, which are used in the same context.

• The accessibility planned for a product can be defined, documented andverified (e.g., as part of a quality plan).

TARGET AUDIENCE

Who will be using such an ISO document? Today, many organisations have usercentred design groups within the organisations to take the responsibility foraccessibility issues.

ISO Technical Specification 16071 serves the following types of users:• the user interface designer, who will apply the guidance during the

development process.• the developer, who will apply the guidance during design and

implementation of system functionality.• the buyer, who will reference the Technical Specification during product

procurement.• evaluators, who are responsible for insuring products meet the

recommendations of the Technical Specification.• designers of user interface development tools and style guides to be used

by interface designers.

The ultimate beneficiary of this Technical Specification will be the end-user of thesoftware. Although it is unlikely that the end-users will read the TechnicalSpecification, its application by designers, developers, buyers and evaluatorsshould provide user interfaces that are more accessible. The guidelines concern thedevelopment of software for user interfaces, however, those involved in designing


the hardware aspects of user interfaces may also find them useful.

Here is one of the major problems that I think we have observed and that I wouldwant to discuss. How does the reader find the ISO-standard that is applicable tothem in a specific situation? One-stop-shopping could be achieved if all thestandards within ergonomics could be collected under one ISO-number.Alternatively one could create a technical report with the purpose of explaining thedifferent standards and their interrelationship and possible use.

I could also fancy discussing the use of checklists to communicate knowledge.

The importance of making the presentation of the material attractive – today manypeople regard the standards as so boring that one could die...

WHAT TYPES OF CAPABILITIES DO WE WANT TO ADDRESS?

The user characteristics of people with any given disability vary significantly justas any other heterogeneous population. The descriptions contained here provideonly an outline of the issues typically encountered by individuals with variousdisabilities, and do not constitute a comprehensive list. People may concurrentlyexperience more than one of the disabilities outlined below. The needs of peoplewho have such combinations of disabilities are covered in several cases by theoverlap across guidelines.

The following capabilities are specifically addressed in this standard• users who are blind• users who have low-vision• users who are deaf• users who have hearing impairments• users who have physical impairments• users who have cognitive impairments• users who are elderly• users who have temporary disabilities• users who have multiple disabilities• users who have environmental disabilities

Issues commonly encountered by users who are blind

The primary issue for users who are blind is how to obtain information providedby visual presentation, how to navigate among objects on screens, how to identifythose objects, and how to control focus, navigation, and other functions via thekeyboard.

Many people who are blind from birth learn Braille, and many who becomeblind later in life often rely on additional auditory methods to obtain information.

Many users who are blind often have some vision and primarily interact withcomputers through “screen readers” -- assistive software that can provide spoken or


Braille information for windows, controls, menus, images, text and otherinformation typically displayed visually on a screen.

Considerations for these users follow from the characteristics of interactionsmediated by screen readers. To the extent that interactions depend onunderstanding a spatial metaphor for navigation or seeing a graphically representedobjects, users who are blind are more likely to encounter difficulties, and normallykeyboard navigation is an essential function.

In addition, because many users who are blind are reading screens by meansof synthesised speech output, they may find it difficult or impossible to attend toauditory outputs that occur while they are reading.

Issues commonly encountered by users who have low-vision

The issues commonly faced by users who have low-vision include loss of visualacuity, colour perception deficits, impaired contrast sensitivity, and loss of depthperception.

People who have low-vision use varying means of increasing the size,contrast, and overall visibility of visual displays depending upon their visualneeds. Common assistive technologies include use of oversized monitors, largefonts, high contrast, and hardware or software magnification to enlarge portions ofthe display.

When interacting with computers, these users may not detect size coding,have difficulty with font discrimination, and encounter difficulties locating ortracking interface objects such as pointers, cursors, drop targets, hot spots, anddirect manipulation handles.

Additionally, both blind and users who have low vision experiencedifficulties when required to read very small displays, such as those on printers,copiers, ticket machines and ATMs.

Issues commonly encountered by users who are deaf or hard of hearing

Users who are deaf or hard of hearing who retain some functional hearing includethe inability to discriminate frequency changes, decreased frequency range anddropout, difficulties localising sounds, and difficulty picking up sounds againstbackground noise.

Users who are deaf or hard of hearing may or may not use electronic hearingaids, depending on the nature and extent of the hearing impairment. If it isavailable in the operating system, they may use the “ShowSounds” feature thatnotifies software to present audio information in visual form.

When interacting with computers, these users may have trouble hearingsounds of certain frequencies, or of low volume. Sound customisation is key toproviding them with access.

Issues commonly encountered by users who are deaf


In addition to a general inability to detect auditory information, the issuescommonly faced by users who are deaf may include the inability to produce speechrecognisable by voice input systems, and experience with a national language onlyas a second language (sign language often being the primary language for peoplewho are born deaf or who become deaf at an early age).

If it is available, users who are deaf will typically use the “ShowSounds”feature that notifies software to present audio information in visual form.

When interacting with computers, these users will encounter problems ifimportant information is presented only in audio form. Many of these issues applyto any user in contexts where sound is masked by background noise (e.g., machineshop floor) or where sound is turned off or cannot be used (e.g., a library).

Issues commonly encountered by users who have physical impairments

The issues commonly faced by users who have physical impairments often followfrom physical limitations including poor co-ordination, weakness, difficultyreaching, and inability to move a limb.

Users with physical impairments may or may not use assistive technologiesand the variety of hardware and software they employ is too large to describe indetail in this space. A few examples, however, include eye-tracking devices, on-screen keyboards, speech recognition, and alternative pointing devices.

Some users may have difficulty directly manipulating objects, using modifierkeys, using pointing devices, and performing actions that require precisemovement or timing. Other users may have tremors that cause difficulty inmoving to a target. The extreme variation in needs and capabilities among thisuser population means that customisation of input parameters and timing isextremely important for effective access.

Issues commonly encountered by users who have cognitive impairments

The issues commonly encountered by users who have cognitive disabilitiesinvolve difficulties receiving information, processing it, and communicating whatthey know. People with these impairments may have trouble learning new things,making generalisations and associations, and expressing them selves throughspoken or written language. Attention deficit hyperactivity disorders make itdifficult for a person to sit calmly and give full attention to a task.

The issues commonly faced by users who have dyslexia are difficultiesreading text that is presented in written form and difficulties in producing writtentext.

Reading difficulties is best supported by having the text that is highlightedand read out loud or by providing “easy-reading” versions of the texts. Userswithout reading difficulties also benefit from easy-reading versions of written text.

Providing support of synthetic speech for what is to be written best supportswriting difficulties.


Issues commonly encountered by users who are elderly

Elderly users are progressively limited in their ability to use and access human-computer interfaces due to the multiplicative effects of combinations of visual,hearing, cognitive, and motor impairments that to varying degrees might comewith increasing age.

Sometimes the awareness of diminishing capabilities is a concern for elderlyusers. Therefore, built-in accessibility of products contributes to removing thestigma of special aids or modifications. Elderly persons do not want to have theirage regarded as a disability.

Issues commonly encountered by users who have temporary disabilities

Temporary disabilities are often of a physical nature (e.g. broken arm). These usersseldom adopt efficient skills in learning to cope with their disability. It is thereforeimportant to make the accessibility features for these disabilities easy to find andlearn to master.

Temporary disabilities might also be caused by repetitive strain caused bypoor ergonomics and intensive use of the computer system. It is then importantthat this injury can be relieved through support that can be provided to the user viathe system.

For example, improving the design of the laptop computer so that it can beopened with one hand also increases the usability for all users.

Issues commonly encountered by users who have multiple disabilities

There are not just a few categories of disabilities, rather the range of differentaccessibility needs varies just as the combinations of certain degrees of disabilitiesare a fact. For example, an individual with a cognitive impairment might also havelow vision.

Several of the guidelines for addressing a specific disability might becontradictory. For example, auditory output of written text is not a support for thedeaf blind. It is therefore important that the support for these forms of multipledisabilities is individualised for the specific user and task.

Issues commonly encountered by users who have environmental disabilities

Environmental disabilities occur when specific features of the work environmentcause difficulties in perceiving signals from the computer. Such situations includedifficulties hearing signals from the computer, working in a noisy environment.These situations must be regarded as disabling the user to fulfil the task with theaid of the computer. Although this may not be a software requirement, theimmediate solution should be to improve the environment, and, in situationswhere this can not be made, such as airports, provide redundant presentations ofessential information.


WAI GUIDELINES

The W3C has provided one of the most commonly used documents onaccessibility. The ISO working group had quite a discussion on whether thematerial could be regarded as stable and how a standard could reference guidelinesthat merely are provided on-line. The group went through all of the guidelinesprovided in [W3C, 1999] and grouped them into the following categories;• guidelines that are already covered by ISO 9241• guidelines that are not of a general nature• guidelines that should be included in the document.

The following decisions were made...

SUMMARY AND POSSIBLE FUTURE DEVELOPMENT EFFORTS

ISO TS 16071 Ergonomics of human-system interaction – guidance on softwareaccessibility will be published by the end of 2000. The intention of the group is tomove the document further and pursue the work to be an international standard.

ACKNOWLEDGEMENTS

The authors wish to acknowledge the entire subgroup on accessibility from ISOTechnical committee 159/Sub committee 4/Working Group 5. The input providedby Human Factors and Ergonomics Society in terms of their outline of theaccessibility part of ANSI 200 is a significant contribution to the making of thetechnical specification.

REFERENCES

International Organization for Standardization (1998) ISO 9241 Softwareergonomics with visual display terminals (VDTs), Part 11 Guidance on Usability.International standard. (Switzerland: International Organization for Standardization)

International Organization for Standardization (1999) ISO 13407 Human centreddesign process for interactive systems. International standard. (Switzerland:International Organization for Standardization)

International Organization for Standardization (2000) ISO 16071 Ergonomics ofhuman-system interaction – guidance on software accessibility. TechnicalSpecification. (Switzerland: International Organization for Standardization)

Userfit

Thorén, C. (ed.) (1998). Nordic Guidelines for Computer Accessibility. 2nd ed.,(Vällingby: Noordic Cooperation on Disability).


World Wide Web Consortium (W3C), (1999) WAI - Web content accessibilityguidelines 1.0, May 5, 1999.

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